Create a visualization of where phonological data comes from

[thatbudakguy]

It would be helpful to try to visualize the current state of phonological data as a grid of small boxes, almost like GitHub's activity graph:

In such a visualization, each box would be a single character. Color (and shading?) could be used to indicate the state of known phonological data for that character:

• Complete (only one valid reading from reconstruction, or reading given directly by LDM)
• Incomplete (sources are ambiguous; not fully specified)
• Missing (no source for the data)

This would help point to regions of the data that are in need of more work.